title: Magnetic field observations as Voyager 1 entered the heliosheath depletion region.
abstract: Magnetic fields measured by Voyager 1 (V1) show that the spacecraft crossed the boundary of an unexpected region five times between days 210 and ~238 in 2012. The magnetic field strength B increased across this boundary from ≈0.2 to ≈0.4 nanotesla, and B remained near 0.4 nanotesla until at least day 270, 2012. The strong magnetic fields were associated with unusually low counting rates of >0.5 mega-electron volt per nuclear particle. The direction of B did not change significantly across any of the five boundary crossings; it was very uniform and very close to the spiral magnetic field direction, which was observed throughout the heliosheath. The observations indicate that V1 entered a region of the heliosheath (the heliosheath depletion region), rather than the interstellar medium.
authors.affiliation: NASA-Goddard Space Flight Center, Greenbelt, MD 20771, USA. lburlagahsp@verizon.net
authors.forename: L F
authors.initials: LF
authors.lastname: Burlaga
authors.forename: N F
authors.initials: NF
authors.lastname: Ness
authors.forename: E C
authors.initials: EC
authors.lastname: Stone